Hey Greenearth. Just recently finished my own lr2's in hydro. couple things that may influence your decision:
1) wheter or not you have fem'd lr2 seeds... if you have regular seeds, you'll want 1 hydro tub per plant. if you use a shared rez with these, the roots will entangle (more quickly than you would think) and you will damage the female plants that you want to keep.
with fem'd seeds. Go ahead and use a big rubbermaid bin and let'm share that rez. just start them at the same time so you don't run into ppm issues (these babies are VERY easy to nute burn so you need them all the same age, needing the same stuff at the same time).
2) what lr2's lack in height, the more than make up for in horizontal growth. They'll try and bush out on ya. If crunching them in together tightly, you'll need to lollipop them. Or you could consider a smaller version of scrog with less plant as well.
3) type of hydro grow should be dependent on various factors such as $, space, and effort you're willing to put in. I did mine with a ghetto-style dwc-bubbler. Whole thing cost me under 50 easily. Just need to change the rez and clean it up every other week. I will put out this disclaimer...when in doubt, oversize your rez! Of my last grow, only 1 of my female lr2's ended up being worthy of growing out. She had her own 3 gallon rez. Towards the end (like the last 4 weeks), she would drink a full gallon of water a day. With 6 plants in there, just be prepared.
On a side note, if you're looking for a quick, fast grow, you should consider a non-autoflowering grow that starts from clone (SOG, perpetual harvest). When you start those 12/12 from clone, they finish in 8-9weeks...the same as the lr2 will do from seed.
Also, not sure about your seed access but you may want to look at some of the autoflowering hybrids that they have now. Just 2 more weeks difference from lr2 harvest time and they tend to be considerably stronger smoke-wise (no offense to lr2's, mine kinda kicks my ass
)
Good luck.